Drier



Nov. 3, 1931. R. P. DE VRIES DRIER Filed April 8. 1929 2 Sheets-Sheer.

Vlllll VIII! I III/Ill "III! INVEN 0R. ERzyZpe fies, BY 2 a ATTORNEY.

n .0 am m T 0 1 Hm W atented ov. 3, 1931 ED STTES ATENT OFICE DRIER Application filed April 8,

This invention relates, generally, to improvements in apparatus for drying pulverulent or granular materials; and the invention has reference, more particularly, to a drier especially adapted for drying bone black or char, which has been used for filtering sugar syrups in the process of manufacturing sugar, preparatory to reburning or revivifying the same.

This invention has for its principal object to provide a novel construction of drier for general use in drying pulverulent or granular materials, but which is especially useful for drying bone black or char in connection with 1 the processes of manufacturing refined sugar;

with this object in view, the drier is constructed to provide means for disposing the material to be dried in a relatively thin layer or mass subject to the transverse discharge 2 uniformly therethrough of heated air at comparatively low pressure, such heated air being adapted to quickly absorb moisture therefrom, which moisture is carried off with the discharged air, whereby the material is quickly and efliciently dried; and to this end the drier comprises means to provide an air chamber contiguous to which a drying passage is formed by laterally spaced substantiall vertical tiers of inwardly and downwarc ly inclined opposed louvers, whereby the material to be dried may descend and fill such drying passage so as to be exposed to the penetrative transverse flow of heated air entering from the air chamber through the spaces between the louvers of the inner tier and discharging to the atmosphere through the spaces between the louvres of the outer tier.

Other objects of this invention, not at this time more particularly enumerated, will be clearly understood from the following detailed description of the same.

An illustrative embodiment of the invention is shown in the accompanying drawings,

in which:

Figure 1 is a perspective view, with parts broken away, of a drier apparatus made according to the principles of this invention; Figure 2 is in part an end elevation and in part a vertical transverse section thereof,

1929. Serial No. 353,335.

drawn on a somewhat enlarged scale; and Figure 3 is an enlarged fragmentary cross section through a drier passage formed by opposed laterally spaced tiers of louvers, said View being drawn on an enlarged scale.

Similar characters of reference are employed in the above described views to indicate corresponding parts.

When using the apparatus for drying wet bone black or char removed from sugar syrup filters, it is generally the practice to associate thesame with the kilns which are employed to reburn or revivify the char, so that not only may the drier discharge the dried char directly to the kiln retorts, but also that waste heat from the kiln may be utilized in aid of the drying process; in the accompanying drawings I have illustrated the novel drier of the instant invention as arranged for similar association with a char revivifying kiln, although it will be understood that the novel drier may be used independently of such association when employed for materials other than char, in which case heated air may be supplied to the air chamber thereof from any suitably provided or available source.

Illustrative of a construction of drier em-v bodying the principles of my present invention I have shown the same to consist in vertical transverse end frames 5 and intermediate frames 6 spaced longitudinally apart, said intermediate frames 6 having central openings 7 so as to provide interconnecting spaces between the end frames 5 adapted to form an air chamber 8. Said air chamber 8 is closed at its upper side b transverse horizontal top plates 9 exten ing between the frames 56, and is closed at its lower side by transverse bottom plates 10 also extending between the frames 56. Said frames 5-6 are supported on I-beams 11 connected with the brick work 12 of the furnace of the underlying kiln, and preferably in I such arrangement and relation that the bottom of the air chamber 8 overlies and is contiguous to a discharge flue 13 leading from the kiln furnace, and through which hot ases of combustion are discharged thererom. In order to utilize the waste heat of the flue gases from the kiln furnace to aid in maintaining the air delivered into the air chamber 8 at desired temperature, and also as a means for producing preliminary drying effects upon the char pr1or to delivery thereof to the main drying passages to be subsequently described, a flue 14 is rovided above and contiguous to the top 0 the air chamber 8, the top of the same being formed by inverted V-shaped plates 15 connected between the frames 5-6 and spaced above the top plates 9 and the sides of which are preferably provided by louvers 16. Said flue 14 is provided with a discharge opening 14', which may be connected with a chimney or stack (not shown). Said fiues 113 and 14 are connected in communication by means of a connecting flue pipe 17 which extends from the flue 13 diagonally upward to the flue 14 through the interior of the air chamber 8.

Provided at the upper end of the drier is a char feed hopper 18 formed by inwardly and downwardly inclined hopper plates 19 which converge toward the sides of the V- shaped plates 15, but the lower ends of which are spaced from the latter to provide discharge mouths 20. Slidably mounted to cooperate with said discharge mouths 20 are movable cut-ofi plates 21, which may be positioned at will to close or open said hopper discharge mouths 20 as occasion may require. Contiguous to thesides of flue 14 formed by the louvers 16'is a descending passage 22, the outer side of which is provided by side plates 23 suitably mounted between the frames 5-6. The main drier passages are provided contiguous to the sides of the air chamber 8. These drier passages are formed by wing plates 24 extending from the marginal portions of the frames 5-6, either as a connected or integral part thereof, and, if desired, additional wing plates 24' may be provided intermediate said wing plates 24. Secured to and extending between said wing plates are laterally spaced tiers of downwardly and inwardly inclined vertically spaced apart louvers, comprising an inner tier of louvers 25 and an outer tier of louvers 26, between and by which is formed substantially vertical drying passages or chambers 27 of comparatively narrow transverse width relative to the height thereof, so that the char or other material, when filling the same, is disposed in a comparatively thin layer of considerable surface area. Arranged in communication with the upper ends of the drying passages or chambers 27, and intermediate such ends and the lower ends of the passages 22 leading from the feed hopper 18, are funnel-like receiving mouths I 28 formed by inner and outer plates 29 and 30, which converge upon said upper ends of the drying passages or chambers 27. Arranged beneath the lower ends of the drying passages or chambers 27 are discharge hoppers 29 formed by inclined plates 30 and 31 which converge toward each other to form discharge mouths 32. Slidably mounted to cooperate with said discharge mouths 32 are movable cut-off plates 33, which may be positioned at will to close or open said discharge mouths 32 as occasion may require.

Extending beneath said discharge hoppers 29 are distributing chutes 34 for conveying away the dried char or other material discharged from the drier passages or chambers 27. When the drier is associated with a char revivifying kiln, the feed pipes 35 of the latter are arranged to open into or communicate with the chutes 34 through the bottoms thereof, whereby the dried char discharged from the drier may flow under gravity into the retorts of the kiln, being there reburned or revivified and then discharged from said retorts through the cooler pipes in the manner well known to those skilled in the art.

Oonnectedin communication with one end of the air chamber 8 of the drier is an air delivery pipe 36', through which heated air may be delivered from any suitable source into said air chamber 8. The air may be propelled through said delivery pipe by afan (not shown) so that a substantially constant Volume of air at desired relatively low pressure may be maintained in said air chamber 8. When the drier is used for char and is associated with a char revivifying kiln means may be provided for conducting air contiguous to the cooler pipes of the kiln, so that the heat radiated from the latter may be utilized to raise the temperature of the air, such air being thereupon conducted through the air delivery pipe 36 to the air chamber 8 of the drier.

In operation, the wet char is deposited in the feed hopper spaces 18 and, the cut-off plate 33 being closed and the cut-off plate 21 being opened, is allowed to gravitate through the descending passages 22, receiving months 28, and thus into thedrier passages or chambers 27 until the same are filled. Heated air under a pressure slightly in excess of atmospheric pressure is supplied to the air chamber 8,- whereby an. outward movement or flow of heated airat low velocity is caused to traverse the char filled drying passages or chamber 27 as such heated air passes through the spaces between the inner tier of louvers 25 and discharges through the spaces between the outer tier of louvers 26. The heated air, within the air chamber 8, which is very low in moisture content, is forced through the layer of wet char formed in the drying passages or chambers 27, and in contacting with such wet char will rapidly absorb moisture therefrom so as to be discharged in a saturated condition and at a reduced temperature, and at the same time the heat of the air operates to change some of the moisture into water vapor which is likewise carried off from the char with the discharging air. Since the wet char mass in the drying passages or chambers 27 is of substantially uniform thickness throughout its extent, and since the drying passages are contiguous throughout their lengths to the interior air chamber 8, the resistance to air movement is substantially constant at all points throughout the surface area of the mass of char, and consequently the drying eifect is uniform throughout the entire surface area of the mass orlayer of char. The inner portions of the mass or layer of char which receives the firstcont'act of heated air becomes dry, and as its moisture is removed will be raised in temperature until its temperature equals that of the heated air. This action progresses transversely through the entire mass or layer of char until its outer portions in turn become dry.

There is no risk of escaping dust during :the drying operations since the air leaves the drier fully saturated and at very low velocity, due in part to the decrease in volume incident to the lowering of temperature thereof as it traverses the wet char. Even when the char is completely dried and the air is not reduced in volume, there is substantially no emission of dust for the reason thatthe initial velocity of air movement is kept low (preferably about 20 to 30 feet per minute).

From the above it will be obvious that the drier operates on the following principles:

First. That moisture is and can be absorbed by relatively dry air in the form of a transparent or invisible vapor until a humidity of 100%, or the saturating point, is reached.

Second. That the amount of vapor that air can carry depends on the temperature and pressure of the air; and that the higher the temperature and the lower the pressure 'of the air, the greater is the amount of moisture it can absorb and hold.

Third. That for every degree rise in the temperature at a constant pressure, dry air i s capable of absorbing and carrying 5% more moisture, so that its capacity may be doubled with a rise of temperature of about 20%.

Fourth. Since air at high temperature and lOW pressure will normally have a very low moisture content it will carry but a negligible quantity of latent heat, and consequently may be quickly heated and rapidly cooled.

Under the conditions and principles above suggested it will be understood that the drier operates as an air drier under substantially constant pressure conditions as to initial contact of the air with the material to be dried, and under substantially constant humidity drawings and above described,{ the drying operations may be caused to ta e place in a substantially continuous manner, by so adjusting the intake and outlets of the drying passages or chambers that there is established .a slow continuous movement under gravity of the char through the latter from the feed hopper spaces 18 to the chutes 34 as W111 be understood. Advantage may also be taken of the passage of the char through the descending passages 22 contiguous to the louvers 16, whereby the heat of the hot flue gases will be transferred to the char while in the passages 22 so that this heat may be utilized to convert some of the moisture content of the char into steam which may escape through the spaces between the louvers 16 into the flue 14 so as to be carried ofli with the flue gases flowing through the latter.

It will be understood that the novel drier may be constructed in various ways as to its detail design given the essentials of an air chamber having a louver bounded drying passage or chamber contiguous thereto and in communication therewith; and, furthermore, that the drier having the aforesaid fundamental features of construction may be employed for many different kinds of pulverulent or granular materials other than char.

Having thus described my invention, I claim 1. In a char drier, means to provide an air chamber adapted to be supplied with heated air, laterally spaced substantiall vertical tiers of louvers contiguous to a si e of said air chamber to form a main drying passage within which char to be dried is disposed in a substantially uniform relatively thin layer through which heated air may discharge from said air chamber directly to the atmosphere, a feed hopper means for delivering wet char into the upper end of said drying passage, a flue pipe for thefpassage of hot products of combustion arranged to ex tend through the interior of said air chamber and adapted to transfer heat to the air in sa1d air chamber, and a discharge flue underlying said feed hopper means and communieating with said flue pipe, said discharge flue being adapted to radiate heat to said feed hopper for the preliminary drying of char fed by the latter to said main drying passage.

' 2. In a char drier, means to provide an air chamber adapted to be supplied with heated air, laterally spaced substantially vertical tiers of louvers contiguous to a side of said air chamber to form a main drying passage with- 5 in which char to be dried is disposed in a substantially uniform relatively thin layer through which heated air may discharge from said air chamber directly to the atmosphere, a feed hopper means for deliver ing wet char into the upper end of said drying passage, a flue ipe for the passage of hot products of com ustion arranged to extend through the interior of said air chamber and adapted to transfer heat to'the air in said air chamber, and a discharge flue underlying said feed hopper means and com municating with said flue pipe, said discharge flue bein adapted to radiate heat to said feed hopper or the preliminary drying of char ,fed by the latter to said main drying passage,

manipulatable means to control the flow of char from said feed hopper means to said main drying passage, and manipulatable means to control the discharge of dried char 2 from said main drying passage.

.In testimony that I claim the invention set forth above I have hereunto set my ban this 30th day of March, 1929.

R.-PAUL DE VRIES. 

